The present invention relates to microelectromechanical systems (MEMS) and in particular, to a MEMS device used to measure strain.
Conventional strain gauges are made of wire or foil (metal) or a semiconductor material that is mounted to the surface of the object. As the underlying object is strained, the strain is transferred to the strain gauge material and a change in electrical resistance is exhibited proportional to the deformation (i.e. strain) of the strain gauge material. In addition to resistance, capacitance, inductance or reluctance may also be used to establish a measure of strain. Some semiconductor strain gauges are made of a piezoresistive material such as silicon. As the piezoresistive material is stressed, the fundamental materials properties of the material change causing the resistance to change. This change in electrical resistance is measured to provide an indication of the stress in the piezoresistive material and therefore also an indication of the strain in the underlying object.
MEMS devices are extremely small machines fabricated using integrated circuit techniques or the like. The small size of MEMS devices makes possible the mass-production of high-speed, low-power, high sensitivity, and high-reliability mechanisms that could not be realized on a larger scale.
It would thus be desirable to provide a MEMS device that can be mounted onto an underlying object that is operable to provide an indication of strain experienced at the object. It would furthermore be desirable to measure the strain at a plurality of locations over an area.